Soldier turtle ants are an excellent laboratory of evolution in themselves. And they show that evolution is reversible. Trees usually inhabit. They have shiny, oversized heads, which they use to block the entrances of their nests. The exceptional thing is that their heads adapt to work like perfect doors.
The shapes of their heads vary. Some are somewhat rounder. Others are square, and assemble in multi-member locks like a Spartan army. This explains how species evolve to fill ecological niches.
Evolutionary round trip
"Generally, one would think that once a species specializes, it becomes trapped in that very narrow niche." It says it's a statement Daniel Kronauer. He is the head of the Rockefeller Evolution and Social Behavior Laboratory. But turtle ants are an interesting case of a very dynamic evolutionary trajectory. With a lot of back and forth ».
The shape and size of the head of a soldier turtle ant is dictated by the type of tunnel the species in question occupies. Ants do not dig tunnels. They move to those excavated by wood beetles. A down tunnel could be too big or too small, says Kronauer. So the ants quickly diversify to be able to occupy it. That is, their heads adapt to the hole, in order to function as a specific block.
The evolutionary analysis of these ants shows a surprising feature. The oldest common ancestor had a square head. That ancestor went on to form a variety of species, with different levels of specialization. In some cases, more specialized species reversed direction over time. What does this mean? That evolution is reversible, of course. Thus, ants evolved back to more general head shapes.
The finding shows very well how surprisingly flexible nature can be. The shape of an organism can be adapted to the context of the environment it occupies.
"The space evolution has to play with is actually quite a bit larger than previously thought," adds Kronauer.